# Questions tagged [grid-deduction]

Puzzles such as Sudoku or Kakuro, where the final state of a pre-existing grid must be deduced logically through clues placed within and/or around the grid. Use with the [logical-deduction] tag. For puzzles where you are given a list of clues which can be used to compose a grid to solve them logically, use the [logic-grid] tag instead.

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### Introducing: Jormungand

An entry in Fortnightly Topic Challenge #32: Grid Deduction Hybrids Introducing: Jormungand A combination of Ouroboros (Slitherlink) and Numbersnake (Numbrix) to create the greatest snake-themed ...
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### A Knight's Kuromasu

An entry in Fortnightly Topic Challenge #32: Grid Deduction Hybrids You are a knight in the king's army, and you've been tasked with constructing some walls. The problem is, as a knight, you are ...
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### Arrangement at the puzzling class

PSE open a puzzling class. 16 students join the class. the classroom have 16 chairs arranged in (4 x 4) grid. ...
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### Messages hidden in the "visit every square once" puzzle

I proposed my girlfriend yesterday, asking her to be my wife. but she did not answer me. Besides she gave me this 6 puzzles, below. She said I will know her answer after solving the puzzles. Inside ...
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### Hexagonal Kurokuron

Kurokuron (クロクロ一ン: "black clone"), is a shading puzzle that first appeared in Puzzle Communication Nikoli issues 153-155. Identical rules apply to a hexagonal grid. Rules Shade some cells such that: ...
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### Nested sudoku in entrance exam

My university (Keio university in Japan) set this question in 2013's entrance exam. The red boxes include numbers from 1 to 9. What's the solution for this sudoku?
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### Can you solve this kakuro puzzle?

This kakuro puzzle comes from the newest edition of Topple, an indie puzzle magazine I run. For those who are unfamiliar with kakuro, here are some instructions: Kakuro consists of a blank grid with ...
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### The Determinant Sudoku

The determinants of $2\times 2$ matrices are calculated this way: $$\det\begin{bmatrix}a & b \\c & d \end{bmatrix}=ad-bc$$ And here's the sudoku-determinant puzzle: What's the solution for ...
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### 36-length snake in a 6x6 grid

Based on https://brilliant.org/weekly-problems/2017-05-29/advanced/?p=4 We need to fill a 6x6 grid using the numbers 1-36, each cell having a single unique number, such that: Every two consecutive ...
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### Difference square logic (5x5)

Rules : Arrange numbers 1 to 25 to the squares, and each number only occurs once. Green squares are the difference from its left square and its right square. Green squares are also the difference ...
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### Trapezoids Compound Hidden Puzzle

UPDATE To refute Sconibulus's answer, I drafted a second puzzle with identical rules. 7 months ago, I released a collection of variations of an original puzzle called Trapezoids, but never mentioned ...
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Rules: Hey, this looks like slitherlink! In fact, it is two slitherlinks added together. So both of the two slitherlinks have clues in exactly the same locations as this grid below. Furthermore, a 2 ...
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### Karst - A variant of Cave

This is a variant of Cave applied to a 3.4.6.4; 3.42 6; 44 tiling. Rules Draw a single loop along the dashed lines that encloses some cells. Edges of this loop may not cross or share a ...
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### Help! Can you get my puzzle back?

Puzzling has a lot of really complicated stuff these days, so I just wanted to post a simple Boggle grid. You know that game, right? You form words by starting from one letter, then taking adjacent ...
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### Skeleton sudoku, the second

I've already set one skeleton Sudoku. Here's a rather harder one. (Nonetheless, it should be within the realms of what can be done by hand; I solved it manually myself to verify that there was only ...
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### A spartan skeleton Sudoku

A skeleton crossword is a crossword where the black and white squares aren't given; you have to deduce them. Here's a generalisation of that idea to the Sudoku puzzle. Here's a 4 by 4 grid, with four ...
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### My featured entry

Mosaic is a Minesweeper-like puzzle based on a grid with a pixel-art picture hidden inside. Using logic alone, the solver determines which squares are painted and which should remain empty until the ...
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### ASCII Art Painting

I've been taking an art course recently, and I met someone who was proficient with grid ASCII art paintings. However, the teacher of the class always seemed to think there was something wrong with his ...
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### Who can spot the difference?

My family and I have just moved house! Lucky us! So what did my family do? We held a housewarming party, and rung everyone in the neighbourhood up to invite them. So, anyway, people were coming in ...
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### Ambiguous Grids

After six to eight weeks of waiting, your Shmikoli™ Ambiguous Grid Deduction Puzzle Set has finally arrived! You tear into the box only to discover that the instructions are missing. You shouldn't ...
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### Oriental House: An original grid-deduction challenge

A different approach to an old concept of mine, Oriental House is a new grid-deduction puzzle based once again off exits and entries. The rules are as follows: Draw a path from S to F, passing ...
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### What is a "unique solution" in a Slitherlink puzzle?

In the question Five Slitherlinks, the querent suggests that "each [Slitherlink puzzle has] a unique solution". I'm newly reading about Slitherlinks, but I don't understand what makes a ...
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Solve five Slitherlinks, each with a unique solution. Please say a word regarding (or show an image depicting) each solution method.
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### Move the coin in the color grid

You need to move the Coin from the S(tart) cell to the END cell. Rules: From S you can move to cells 2,7 or 8. From BLUE cells you can only move ONE space diagonally. From YELLOW cells you can only ...
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### Sudoku with only 8 predefined numbers

Have fun with my self-made Sudoku puzzle. Solve this Sudoku puzzle using the standard Sudoku rules: Fill any row, column and bold-framed area with the numbers 1 to 9. Hint: It is not as difficult as ...
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### Cairo pentagonal tiling logic grid (Edit : with more clues)

Rules : Fill with numbers from 1 to 13, and each number can appear max 4 times. Small numbers between 2 cell shows the difference between the cells. A + D = B + C Example : (In this example, I fill ...
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### Solve the Mosaic

Mosaic is a Minesweeper-like puzzle based on a grid with a pixel-art picture hidden inside. Using logic alone, the solver determines which squares are painted and which should remain empty until the ...
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### Sudoku embedded in a Kakuro

In addition to standard Kakuro rules, the grey shaded cells must form a valid Sudoku solution. One sum in this puzzle has been corrected from 28 to 23. Fortunately, it was in a location that nobody ...
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### Logic 5x5 Letter Number Combination Grid

Hey I just thought other might enjoy the challenge of this puzzle as much as I did. Not the most easy thing to solve. Sort of like Sudoku, each row and column needs the letters A,B,C,D,E and each row ...
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### Creating a Kakuro puzzle with a unique solution

I start with a grid of black and white cells. I randomly populate the white cells from numbers (1-9) using Kakuro rules. Then I calculate the horizontal and vertical sums. I remove the numbers from ...
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Title hint:
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### Three for the price of one

While browsing through your local puzzle store, you see something you can't resist: a box which promises two grid deduction puzzles for the price of one! The vendor explains that the box contains a ...
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### Curiouser and Curiouser

CHAPTER ONE Alice was beginning to get very tired of sitting by her sister on the bank, and of having nothing to do: when she was overcome with the strangest sense of deja vu, and saw a 7x3 grid of ...
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### Build your own™ Dominosa!

Fictional story: As everybody knows I'm not good at making puzzles so I ordered a Build-your-own™ Dominosa kit! This should be good for my Dominosa building skills, I thought to myself. And today, ...
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Note: This is not asking for a general strategy, you can find that here. Is the following a valid strategy in solving Numberlink (Flow Free) puzzles (I like to call it 'unwrapping the grid'): ...
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### Introducing Domidoku!

Come one, come all! Come see the new type of logic puzzle, the Domidoku! Here's a sample for all to try! The process is simple! First you solve the Sudoku and then you solve the Dominosa! ...
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### Non-Congruent Fillomino

Here's a Fillomino puzzle (rules can be found here). The gimmick is that no two areas can be congruent. Enjoy!
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### This puzzle design was a DISASTER!

As any member of the PSE community knows, grid-deduction puzzles really aren't my forte. In fact, I'd like to share one particularly disasterous attempt at designing a Slitherlink puzzle. Disclaimer:...
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### Revenge of the Cryptic Crossword Sudoku

This puzzle is inspired by Matt’s excellent Cryptic Sucrosswordoku. Below is a sudoku as well as some cryptic clues. The clues lack enumeration and are in no relevant order. The solutions to the ...
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### Is ambiguity prevention sufficient reason to infer a clue?

I decided to work my way through Simon Tatham's puzzle collection to broaden my puzzling skills, and have reached the game Dominosa I have a subboard below, where I've eliminated the possibility of 9/...
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### Treasure of the fancy island

The colored rectangle below is the map of a fancy island. There is a treasure hidden there, but instead of the usual X on the map to depict the location of the treasure you have the following clues ...
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### Haisu: Pixel Perfect

HAISU is a portmanteau of three Japanese words - 'hairu', to enter, 'su', number, and 'hausu', an English borrow word meaning house, of course. Together, we get a meaning of 'enter number house', ...
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### Haisu: Pink Rose

HAISU is a portmanteau of three Japanese words - 'hairu', to enter, 'su', number, and 'hausu', an English borrow word meaning house, of course. Together, we get a meaning of 'enter number house', ...
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### Cryptic Crossword Sudoku

This puzzle is inspired by Matt’s excellent Cryptic Sucrosswordoku. Below is a sudoku as well as some cryptic clues. The clues lack enumeration and are in no particular order. The solutions to the ...
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### Dividing up land

Historical records indicate that the brothers Geoff, Petro, and Olaf divided up their large rectangular estate between themselves. Unfortunately, evenly dividing up favorable landmarks resulted in the ...
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### Haisu: MathGrant

HAISU is a portmanteau of three Japanese words - 'hairu', to enter, 'su', number, and 'hausu', an English borrow word meaning house, of course. Together, we get a meaning of 'enter number house', ...
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### Coloring a 4 by 4 grid

I made this simple puzzle a couple of years ago. There are three colors which appear in every row and every column. Moreover, every color appears 5 or 6 times in total. Find the color of the square ...
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### Mini Ripple Effect puzzles

I enjoyed this puzzle so much that I created some mini versions of it for fun. I signed up to share them with everyone. The rules are the same: Each region with n cells contains all the numbers from 1 ...
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### HAISU: Nought and Crosses

HAISU is a portmanteau of three Japanese words - 'hairu', to enter, 'su', number, and 'hausu', an English borrow word meaning house, of course. Together, we get a meaning of 'enter number house', ...
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